Collapsible Bilge Pump

ABSTRACT

A collapsible bilge pump includes outer and inner cylinders telescopable between retracted and extended posiions. A piston is movable up and down within the inner cylinder. Check valves in the bottom of the outer cylinder and in the piston permit the pump to take in water at the bottom end of the pump and discharge it from the top end. The collapsible pump is easily stowed, and its short stroke, limited to the length of the inner cylinder, is substantaially easier to perform.

CROSS-REFERENCE TO RELATED APPLICATION

My related and copending Provisional Applicaton No. 61/459,755 was filedon Dec. 20, 2010. That filing date is claimed for this application.

BACKGROUND INFORMATION

This invention is a collapsible, manually operated, bilge pump. The pumpcollapses to approximately 60% of its full operating length for stowage,and extends to full length for use.

Manually operated bilge pumps are commonly used for water removal fromkayaks and other small water craft. A bilge pump is a prudent safetydevice for small boats. Kayakers in particular use them for waterremoval after a capsize.

Commonly used bilge pumps include a cylinder with a piston, piston rod,and handle movable relative to it. The cylinder body includes suitablyvalved intake and discharge ports, and a foam float. Such pumps aretypically about 2.5″ diameter and 20″ high. A pump of that size willlift water from the bottom of the hull and expel it over the cockpit rimof a kayak or gunwales of a canoe. A substantially shorter pump will notperform well. Other pump types, such as foot-operated, are available buttheir popularity in small craft and, particularly in kayaks, is limited.

One problem with typical prior art bilge pumps is the size of the pumpand the difficulty of stowing it in the boat when not in use. In akayak, the pump must be readily accessible, not stowed in forward or aftcompartments, and storing it in the cockpit is difficult because oflimited space. The most common solution for kayakers is to secure thebilge pump on the deck under bungee lines. However, this is alsoproblematic as bungee layouts on decks often do not provide secureattachment and pumps can be lost at sea due to natural boat movements orwashed off the deck by waves. If it is secured on the back deck, it maybe difficult to reach by a seated kayaker, and the pump's presence therecan interfere with common rescue techniques such as the cowboy reentry,the paddle float rescue, and numerous assisted rescues. If secured onthe fore deck, the pump can interfere with paddle strokes, particularlysweep strokes used to turn the vessel. A bilge pump secured on the foredeck may also preclude use of this area for other items the kayakerneeds to be visible and readily accessable, such as navigation charts,tide tables, and the like.

My collapsible design greatly alleviates the storage problem experiencedby small boat operators and kayakers. A 20″ extended pump can becollapsed to 12.5″. And a kayaker can find space for my pump, eitherinside the cockpit behind the seat back, or hung under the fore deck, orattached to the hull between and below the legs.

Another benefit of my invention is the surprisingly improved ergonomicsof its operation. A manual bilge pump is a two-stroke device. The upwardstroke pulls water into a the cylinder below the piston while waterabove the piston is lifted and expelled through the discharge port.Then, the downward stroke transfers water from below the piston to abovethe piston. This water is then expelled on the next upward stroke. In atypical pump, stroke length is determined by the length of the pistonrod which is a few inches less then the overall length (or height) ofthe pump. The volume of water lifted on the upward stroke is the area ofthe cylinder's internal cross-section times the stroke length. Onecommonly available pump has a stroke length of 13″ and stroke volume ofabout 27 cubic inches. This is about a pound of water being lifted bythe operator on each upward stroke. The operator also has to workagainst internal friction of the device. With a kayaker in a seatedposition and pumping out his cockpit, the stroke involves arm movementfrom approximately chest height to head height. This motion is derivedfrom smaller arm and shoulder muscles, such as triceps and deltoidswhich tire easily. In these conditions, stroke frequency is relativelylow.

Compared with the prior art, my collapsible pump has a stroke that isonly half as long, the “work zone” where operator effort is applied islower and more conveniently located in front of the chest, and each pumpstroke lifts only half as much weight of water. In these conditions,strokes are easier, and it becomes natural to stroke at a rate more thandouble the stroke rate for a conventional pump. The net result is thatmy invention pumps faster than a conventional bilge pump with seeminglyless input effort.

SUMMARY OF THE INVENTION

The collapsible bilge pump of this invention includes outer and innercylinders telescopable between retracted and extended positions. Apiston is movable up and down within the inner cylinder. Check valves inthe bottom of the outer cylinder and in the piston permit water intakeat the bottom end of the pump and discharge from the top end. Thecollapsible pump is easily stowed, and its short stroke, limited to thelength of the inner cylinder, is substantially easier to perform.

DRAWINGS

In the accompanying drawings:

FIGS. 1A, 1B are elevation and sectional views of my pump in itscollapsed state.

FIGS. 2A, 2B show the pump, and an enlarged detail, in its extendedstate.

FIGS. 3A, 3B, 3C show the pump, and enlarged details, operating in anupward stroke.

FIGS. 4A, 4B, 4C show the pump, and enlarged details, operating in adownward stroke.

FIG. 5 is an enlarged sectional detail of an alternate configuration.

DESCRIPTION OF THE INVENTION

FIGS. 1A, 1B are elevation and sectional views of my pump 10 in itscollapsed state. An inner cylinder 11 is nested within an outer cylinder12. The top end of the outer cylinder 12 is necked down to a diametermatching the outside diameter of the inner cylinder 11. The bottom endof the inner cylinder 11 is flared outward to a diameter matching theinside diameter of the outer cylinder 12. The flaring and necking areover a relatively short dimension, for example 20 mm, and at arelatively small angle, for example 2 degrees. These cylinders and theirconical portions may be produced by secondary forming of extruded tubes,or by injection molding, or by other known methods.

The bottom end of the outer cylinder 12 includes a fluid inlet checkvalve 13. The inlet valve 13 includes passages 14 for water intake intothe pump intake chamber 15. The passages 14 also act as coarse filtersto prevent large debris from entering the pump. The inlet valve 13includes a top planar valve seat 19. The annular bottom edge of theouter cylinder 12 abuts the valve seat 19.

An inlet valve flap 18 is a flexible membrane of elastomeric materialsuch as viton or neoprene. The inlet valve 13 is a check valve. Inoperation, piston upstroke draws water into the pump inlet chamber 15(below the piston) with the valve flap 18 flexed upward. At the end ofthe upstroke, the valve flap 18 lies back over the valve seat 19 to holdthat water in the inlet chamber 15.

A nozzle housing 30 on the top of the inner cylinder 11 includes abearing through which a pump shaft 20 is movable up and down, and adischarge port 17 to expel water in a generally horizontal direction.Shaft 20 is of a rust-proof material such as stainless steel, brass, orplastic. The shaft 20 includes a handle 21 on its upper end. Its lowerend is shouldered and threaded. A lift check valve 22 includes an axialbore to fit onto the shaft 20 and is secured to the lower end of theshaft by a nut 23. The lift check valve 22 includes a lower body withwater passages 24 through it. The lower body is shouldered to a diameterslightly smaller than the inside diameter of the inner cylinder 11allowing it to slide loosely within the inner cylinder 11. The shoulderof the lower body forms a seat for a lift check valve membrane 26.

The lift check valve membrane 26 is a thin flexible membrane with acircular perimeter and an axial hole. The membrane 26 is mounted on thevalve housing 22 by stretching it over a flange in the axial portion ofthe diaphragm valve housing. The lift check valve 22 is constrained inthis location between the housing shoulder and flange. The diaphragmvalve membrane is typically 0.5 mm thick, and its diameter is slightlyless than the inside diameter of the inner cylinder 11.

The pump shaft 20, lift check valve 22, valve membrane 26, and nut 23together form the piston subassembly.

A flotation collar 35 of a durable foam material fits snugly over theouter cylinder 12 and extends along its length. The flotation collar 35is thick enough to float the entire pump. As an example, the flotationcollar of FIG. 1 is about 2.5″ diameter and volume about 14.9 cubicinches.

FIG. 2 shows the pump in the extended position. Detail A shows thenecking of the outer cylinder 12 mating with the flare of the innercylinder 11 to form a water tight seal. Interference between the twoconical sections creates a wedge lock. The desired angle of the matingconic sections produces a lock sufficient to resist normal pumpingforces, though not sufficient to resist a sharp axial shock or atwisting push. If the angle is too large, the inner and outer cylindersmay not lock. If the angle is too small, one or both cylinders couldfracture from stress, or lock too tightly. Because the pumping operationrequires two hands, one to hold the pump and one to operate the piston,the holding hand can resist the downward force of pumping action andminimize the tendency of the cylinders to unlock.

FIG. 3 shows the extended pump with the piston moving upward. Upwardmotion of the piston creates a slight vacuum pressure under the piston,causing the diaphragm valve to seal against the seat area of thediaphragm valve housing, and the inlet valve 2 to flex off its seat onthe inlet valve housing. If the lower end of the pump is immersed inwater, water will flow into the chamber intake below the piston, andwater above the piston will be expelled through the nozzle 17.

FIG. 4 shows the piston in downward motion. Positive pressure is nowcreated in the chamber below the piston, closing the inlet valve againstits seat and stopping flow in the lower end of the pump. The positivepressure below the piston opens the lift check valve 22 upward, allowingwater to flow into the upper pump chamber. This action transfers waterfrom the lower inlet chamber to the upper discharge chamber fordischarge (on the following upstroke) through the nozzle 17.

While the preferred embodiment utilizes interference of flared andnecked sections of the inner and outer cylinders respectively to limitextension, and to lock the cylinders in position, other arrangementsmight instead be employed. One example is shown in FIG. 5 in whichextension limitation and locking are accomplished with threaded sectionsof inner and outer cylinders. Another arrangement might include tabs onthe inner cylinder and slots in the outer cylinder to limit extensionand lock the cylinders in the extended position.

In the following claims, any terms indicative of orientation (e.g.upper, lower; top, bottom; horizontal, vertical) are meant only tocorrespond with the illustrations and to facilitate an understanding ofthe claimed invention. Such terms are not intended as positivelimitations.

The foregoing description, including any dimensions, of a preferredembodiment is illustrative. The concept and scope of the invention arenot limited by such details but only by the following claims.

1. A collapsible bilge pump including: a hollow outer cylinder with topand bottom ends, a hollow inner cylinder with top and bottom ends, and apiston axially movable up and down within said inner cylinder; saidcylinders axially movable relative to each other between retracted andextended positions, the top end of said outer cylinder and the bottomend of said inner cylinder adapted for mutual sealing engagement in saidextended positions; said outer cylinder including a fluid inlet checkvalve on the bottom end thereof to permit fluid intake into said outercylinder and to prevent fluid backflow from said outer cylinder; saidpiston including a lift check valve on said bottom end thereof for fluidtransfer from said outer cylinder into said inner cylinder; whereby,upward movement of said piston closes said lift check valve to drawfluid through said inlet check valve into said outer cylinder, anddownward movement of said piston closes said inlet check valve and openssaid lift check valve to admit fluid from said outer cylinder into saidinner cylinder for discharge from said top end thereof.
 2. A collapsiblebilge pump as defined in claim 1 wherein said engagement of said innerand outer cylinders is by circumferential frictional contact.
 3. Acollapsible bilge pump as defined in claim 1 wherein said inner andouter cylinders are adapted for mating engagement in said extendedcondition of said pump.
 4. A collapsible bilge pump as defined in claim3 wherein said mating engagement of said inner and outer cylinders isthreaded.
 5. A collapsible bilge pump as defined in claim 1, furtherincluding a foam flotation collar surrounding said outer cylinder.
 6. Acollapsible bilge pump including: an outer cylinder with top and bottomends, an inner cylinder with top and bottom ends, and a piston rodaxially movable in said inner cylinder in reciprocal strokes defined bythe height of said inner cylinder; said cylinders axially movablerelative to each other between retracted and extended positions, the topend of said outer cylinder and the bottom end of said inner cylinderadapted for mutual sealing engagement in said extended positions; saidouter cylinder including a fluid inlet check valve on the bottom endthereof to permit fluid intake into said outer cylinder and to preventfluid backflow from said outer cylinder; said inner cylinder being openat the bottom end thereof, and including a discharge nozzle on the topend thereof; said piston rod including a piston within said innercylinder, and a handle extending from the top end of said innercylinder; said piston including a lift check valve to permit fluidtransfer therethrough from said outer cylinder into said inner cylinder,and to prevent fluid backflow from said inner cylinder; whereby, upwardmovement of said piston closes said lift check valve to draw fluidthrough said inlet check valve into said outer cylinder, and downwardmovement of said piston closes said inlet check valve and opens saidlift check valve to admit fluid from said outer cylinder into said innercylinder for discharge therefrom.
 7. A collapsible bilge pump as definedin claim 6 wherein said engagement of said inner and outer cylinders isby circumferential frictional contact.
 8. A collapsible bilge pump asdefined in claim 6 wherein said inner and outer cylinders are adaptedfor mating engagement in said extended condition of said pump.
 9. Acollapsible bilge pump as defined in claim 8 wherein said matingengagement of said inner and outer cylinders is threaded.
 10. Acollapsible bilge pump as defined in claim 6, further including a foamflotation collar surrounding said outer cylinder.